Evaluation of 400 kV Silicone Insulators Aged under Natural Tropical Conditions

Experience of polymer insulators used in transmission lines has now existed for almost 50 years and are widely used by many electricity companies around the world. Their superior performance under high pollution levels, as a consequence of their hydrophobic surface property, constitutes one of most important advantages. Lightweight, low maintenance cost and resistance to vandalism are also additional advantages of the composite insulators use. A first diagnosis, which includes a complete scheme of electrical, mechanical and physicochemical tests, was performed on 400 kV silicone rubber insulators removed after five years in service in the North/East region of Venezuela. The purpose of this paper is to present a summary of the visual inspection and main electric tests results. Having a short time in operation the insulator surface analysis gives information about the early aging period characteristics where the hydrophobicity can be still recovered. New studies would be planned in the future to find the degradation rate of the polymer insulators at this transmission line.